Also, immunity can be achieved against toxins that have been treated with chemicals so that their toxic nature has been destroyed even though their antigens for causing immunity are still intact. This procedure is used in similar toxic diseases.

And, finally a person can be vaccinated by infecting him with live organisms that have been grown either in special culture mediums or have been passes through a series of animals until they have mutated enough that they will not cause disease but will still carry the specific antigens.

This procedure is used to protect against poliomyelitis, yellow fever, measles, smallpox, and many other viral diseases.